Osteoradionecrosis (ORN) of the mandible is a severe complication that follows ionizing radiation therapy in patients undergoing treatment for head and neck cancer. The radiation dose, tumor location, dental trauma, premorbid state of dentition, and concomitant chemoradiotherapy are thought to be contributing factors for ORN [1–3]. Most patients with head and neck cancer are aged 50 years or more and include those who have dental prosthetic implants [4]. Dental implant surgery and/or the peri-implant tissue condition might represent a possible etiology for ORN. Many researchers have studied and reported the effects of irradiation on dental implant therapy. Most of them have discussed the effect of previous irradiation on the success or failure of the dental implant rehabilitation [5–7]. In these cases, the dental implant was installed in the irradiated bone. In contrast, little is known about the effects of radiotherapy on dental implants that have previously been osseointegrated and charged [8, 9]. Here, we reported a case of ORN that arose around dental implants placed before radiation therapy.